2 * linux/arch/arm/kernel/time.c
4 * Copyright (C) 1991, 1992, 1995 Linus Torvalds
5 * Modifications for ARM (C) 1994-2001 Russell King
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 * This file contains the ARM-specific time handling details:
12 * reading the RTC at bootup, etc...
14 #include <linux/export.h>
15 #include <linux/kernel.h>
16 #include <linux/interrupt.h>
17 #include <linux/time.h>
18 #include <linux/init.h>
19 #include <linux/sched.h>
20 #include <linux/smp.h>
21 #include <linux/timex.h>
22 #include <linux/errno.h>
23 #include <linux/profile.h>
24 #include <linux/syscore_ops.h>
25 #include <linux/timer.h>
26 #include <linux/irq.h>
28 #include <asm/thread_info.h>
29 #include <asm/sched_clock.h>
30 #include <asm/stacktrace.h>
31 #include <asm/mach/arch.h>
32 #include <asm/mach/time.h>
37 static struct sys_timer *system_timer;
39 #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \
40 defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE)
41 /* this needs a better home */
42 DEFINE_SPINLOCK(rtc_lock);
43 EXPORT_SYMBOL(rtc_lock);
44 #endif /* pc-style 'CMOS' RTC support */
46 /* change this if you have some constant time drift */
47 #define USECS_PER_JIFFY (1000000/HZ)
50 unsigned long profile_pc(struct pt_regs *regs)
52 struct stackframe frame;
54 if (!in_lock_functions(regs->ARM_pc))
57 frame.fp = regs->ARM_fp;
58 frame.sp = regs->ARM_sp;
59 frame.lr = regs->ARM_lr;
60 frame.pc = regs->ARM_pc;
62 int ret = unwind_frame(&frame);
65 } while (in_lock_functions(frame.pc));
69 EXPORT_SYMBOL(profile_pc);
72 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
73 u32 arch_gettimeoffset(void)
75 if (system_timer->offset != NULL)
76 return system_timer->offset() * 1000;
80 #endif /* CONFIG_ARCH_USES_GETTIMEOFFSET */
82 #ifndef CONFIG_GENERIC_CLOCKEVENTS
84 * Kernel system timer support.
88 profile_tick(CPU_PROFILING);
91 update_process_times(user_mode(get_irq_regs()));
96 static void dummy_clock_access(struct timespec *ts)
102 static clock_access_fn __read_persistent_clock = dummy_clock_access;
103 static clock_access_fn __read_boot_clock = dummy_clock_access;;
105 void read_persistent_clock(struct timespec *ts)
107 __read_persistent_clock(ts);
110 void read_boot_clock(struct timespec *ts)
112 __read_boot_clock(ts);
115 int __init register_persistent_clock(clock_access_fn read_boot,
116 clock_access_fn read_persistent)
118 /* Only allow the clockaccess functions to be registered once */
119 if (__read_persistent_clock == dummy_clock_access &&
120 __read_boot_clock == dummy_clock_access) {
122 __read_boot_clock = read_boot;
124 __read_persistent_clock = read_persistent;
132 #if defined(CONFIG_PM) && !defined(CONFIG_GENERIC_CLOCKEVENTS)
133 static int timer_suspend(void)
135 if (system_timer->suspend)
136 system_timer->suspend();
141 static void timer_resume(void)
143 if (system_timer->resume)
144 system_timer->resume();
147 #define timer_suspend NULL
148 #define timer_resume NULL
151 static struct syscore_ops timer_syscore_ops = {
152 .suspend = timer_suspend,
153 .resume = timer_resume,
156 static int __init timer_init_syscore_ops(void)
158 register_syscore_ops(&timer_syscore_ops);
163 device_initcall(timer_init_syscore_ops);
165 void __init time_init(void)
167 system_timer = machine_desc->timer;
168 system_timer->init();
169 sched_clock_postinit();